1. Field of the Invention
The present invention relates to orthopaedic implants, and, more particularly, to a modular orthopaedic implant having a taper lock joint, and to methods for assembling such modular orthopaedic components.
2. Description of the Related Art
Orthopaedic implants used to reconstruct a joint of a patient typically include two implant halves, with each implant half defining an articulating bearing surface. For example, an orthopaedic knee implant includes a femoral knee component which is placed within the distal femur and a tibial component which is placed within the proximal tibia. The femoral knee component typically includes a metallic articulating bearing surface which pivots on a non-metallic articulating bearing surface defined by the tibial knee component. The non-metallic bearing surface may be formed from a block of ultra-high molecular weight polyethylene (UHMWPE) which is machine to define the articulating bearing surface. The non-metallic bearing surface is attached to and carried by a tibial tray. The tray may in turn be affixed to a stem inserted within the intramedullary canal of the tibia. Pivotal movement between the femoral component and the bearing surface of the tibial component occurs with relatively low friction and wear characteristics.
To accommodate anatomical variations and differing surgical needs, it is known to provide a modular structure for the tibial component, which allows the assembly of different combinations of the bearing, tibial tray and tibial stem to meet the needs presented by the patient conditions. In one such modular structure, the tibial stem for the tibial knee component has a frustum shaped outer surface, and a complimentary tapered receiving member or socket on the tibial tray provides an interference fit in the nature of a morse taper lock between the tibial tray and the tibial stem, for affixing the tibial tray to the tibial stem. It is also known to provide a plug as an alternative to a stem where filling of the receiving member is desirable without an extending stem. Instances where such a plug is desirable include filling the receiving member to prevent debris transmission and providing a threaded plug for receiving an attachment screw to facilitate modular implant assembly.
The present invention provides an orthopaedic device having a first component and a second component having a novel structure providing affixation between components, and which further provides a barrier to contamination flow between the intramedullary canal and the articulating bearing surfaces.
The invention comprises, in one form thereof, an orthopaedic device having a first orthopaedic component including a first end defining an articulating bearing surface and a second end defining a first member of a morse taper lock; and a second orthopaedic component including a first end defining a second member of the morse taper lock. One of the first member and the second member includes a surface having a protuberance thereon.
The invention comprises, in another form thereof, an orthopaedic knee component for implanting within a proximal tibial. A tibial tray includes a proximal tibial plateau and a distally extending socket having an internal surface and defining a female member of a morse taper lock. A tibial plug has a proximal end having a tapered outer surface and defining a male member of the morse taper lock. A protuberance on the outer surface of the tibial plug creates localized deformation when the morse taper lock is assembled.
The invention comprises, in still another form thereof, a method for assembling a modular orthopaedic device. Steps of the method include providing a first component with a female member of a morse taper; providing a second component with a male member of the morse taper lock having a surface thereof with a protuberance thereon; engaging the male member of the morse taper lock with the female member of the morse taper lock; and impacting the second component, seating the second component in the first component and permanently deforming at least one of the protuberance, the female member and the male member.
An advantage of the present invention is that a known taper lock of a modular orthopaedic implant is provided with locking security between the components of the taper lock.
Another advantage of the present invention is that a barrier is formed to inhibit the passage of material between the distal end and the proximal end of a modular tibial implant.